The present invention relates generally to a software metering system suitable for monitoring and/or controlling the usage of software applications.
Software piracy has long been a problem that has plagued software developers. Accordingly, a variety of protection schemes have been developed. One approach is to use a hardware key that plugs into a parallel port at the back of a computer to monitor the usage of selected software running on that machine. Representative hardware keys (also sometimes referred to as dongles in the trade) are marketed by RAINBOW Technologies of Irvine, Calif. Such hardware keys may plug into a standard port such as a RS-232 parallel port. The Rainbow hardware key is understood to contain an 8-bit microprocessor with 32 bytes of non-volatile read/write memory. When developers integrate the use of hardware keys into their software, the keys can be used for a variety of purposes including controlling distribution, software leasing and site license management.
One problem that has been seen in conventional metering devices memory stems from the relatively short life span of the memory devices used therein. To function effectively in software leasing control applications, a meter must have some sort of non-volatile memory that can be frequently rewritten. In external devices such as hardware keys, EEPROMs are normally used as the non-volatile memory. The drawback of EEPROMs stems from their life span which is typically only in the range of 10,000 to 50,000 write/erase cycles. However, such a short life span is often far too short for counter applications. Therefore, metering devices having EEPROM counters have had limited commercial success. The reason is that if a counter goes bad, the user and the licenser may have lost substantially all of the meter's information.
Another problem that has been encountered with existing hardware key based metering devices is that they are not well suited for updating from remote locations. Accordingly, it is desirable for the metering system to be arranged to permit the vendor to remotely add value to the meter.